Specimen Name Result Units Range
Plasma Sodium 136 mmol/L (135-145)
Potassium 2.1 mmol/L (3.5-5.5)
Chloride 94 mmol/L (100-109)
Bicarbonate 29 mmol/L (22-32)
Anion Gap 15 mmol/L (7-17)
Glucose 5.5 mmol/L (3.8-5.5)
Urea 5.7 mmol/L (2.7-7.2)
Urine Sodium 44 mmol/L (> 20)

11yo boy with growth failure and enuresis.
Bartter's Syndrome
  • autosomal recessive - frequently symptomatic in childhood
  • renal juxtaglomerular apparatus hyperplasia:
    • ↑ plasma renin activity
    • ↑ angiotensin I/II & aldosterone secretion
  • normal BP:
    • ↓ vascular response to NA & AT-II ∝ ?downregulation
    • vasodilatation 2° PGE2 & bradykinin
  • hypokalaemia ± alkalosis:
    • ± hypomagnesaemia
    • weakness & periodic paralysis
    • polyuria ∝ nephrogenic DI
    • ↑ prostaglandins → altered Na+/K+ handling

NB - principal defect:

→ ↓NaCl reabsorption in the thick ascending LoH
→ volume depletion → TGF
→ ↑RAS activity

 

Hypokalaemic Metabolic Alkalosis
Diuretics (esp. loop agents) - low Na+, Cl- / high urea
Mineralocorticoid excess - normal-high Na+, Cl- / normal urea
Vomiting / Gastric outlet obs. - very low Cl- / low-normal Na+ / high urea
Diarrhoea / laxatives - low Cl- / normal Na+ / high urea
Post massive transfusion - citrate metabolism & acidosis correction